class Circle extends Shape {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    @Override
    public double calcArea() {
        return Math.PI * radius * radius; // 圆的面积公式：π * r²
    }

    @Override
    public double calcPerimeter() {
        return 2 * Math.PI * radius; // 圆的周长公式：2 * π * r
    }
}